Above: Map showing interventions in Assi River in Varanasi (INTACH)
REPORT TO DIVISIONAL COMMISSIONER, VARANASI
On INTACH’s Pilot Project on Assi Nadi [24th Jan/17 – 26th Feb/17]
Guest Blog by Manu Bhatnagar, INTACH
- INTACH is a national non-profit organization, a registered society under Society’s Act since 1984, having the Secretaries of the GoI Ministries of Environment, Forest & Ganga Rejuvenation, Ministry of Urban Development, Ministry of Culture, DG [ASI] and DG [NM] on its Governing Council with its accounts duly audited by the Office of CAG.
- High pollution load in holy River Ganga at Varanasi is due to domestic wastewater flowing into the river through 33 nallahs and rivulets. Sewerage systems and treatment plants are going to take several years to be in place and effective. In the meantime the river will continue to remain polluted. Based on its experience in Delhi and Agra INTACH has initiated a one month pilot project for cleaning wastewater flow in Assi Nadi using the process of bacterial bioremediation.
3.0 INTACH, as a conscious institutional citizen, initiated a pilot project at its own cost, to reduce pollution in Assi Nadi using low cost unconventional technology. In obedience to directions of Hon’ble High Court, Allahabad, the Director, NMCG, constituted a committee under chairmanship of Commissioner, Varanasi Division for carrying out various improvements related to the Ganga river, which Committee vide its minutes of meeting of 13th June, 2016 and subsequent minutes of meeting dated 19/9/16 granted an NOC to INTACH to carry out a pilot project of pollution abatement of Assi Nadi at its own cost subject to approval by the Committee’s environmental expert, Prof. UK Choudhary, which approval was granted by the learned professor on 28th Oct/2016 after a detailed explanation by INTACH of the proposed process and activities. Subsequently, INTACH mobilized its resources during December, 2016 and implemented the pre-project preparations by 23rd January, 2017.
4.0 The Assi Nadi is some 3.5 km long and meanders through some very densely populated built up areas directly discharging wastewater into the Nadi. All along there has been severe encroachment of the Nadi bed and channel and in the absence of adequate solid waste collection much garbage [including carcasses find their way into the Nadi] The discharge in the Nadi was measured on 3 days for 24 hours each and amounted to 66 MLD [probably 70 MLD as some flow was bypassing the V –Notch]. The water is fast flowing owing to the elevation difference of 27m between origin and river level.
5.0 Several tests of water quality were carried out before start of treatment:
|Sl. No.||Parameter mg/ltr||Near Confluence Point 5/15
|Near Confluence Point 12/16
|6.||Phosphate ( as PO4)||6.2||–|
6.0 Challenges : There were several challenges to be overcome as follows :
- Severe floating garbage disposition
- High velocity of flow giving little retention time for treatment
- Close encroachments on active channel land causing encroaching public to resist interventions which raise water levels
- Several inflows even in the last 300m before river outfall which are difficult to treat in short stretch
7.0 Proposed Solution : To overcome the challenges several interventions were planned and implemented as follows :
- Bioremediation methods would be adopted – bioremediation is the process of removal of pollutants from polluted water (basically organic in nature) with the help of biological products
- Introduction of bacteria concentrates [a precisely balanced blend of naturally occurring, strictly Anaerobic & Facultative live bacterial strains that start dispersing immediately on dilution with water] @ of 100 litres of concentrate per day dozed into the stream at 6 carefully selected locations. The bacteria degrades organic pollutants, enhances dissolved oxygen levels, removes odours.
- Increase retention time by installing soil bag weirs at three locations – this intervention would create a lagoon on the upstream side allowing settling action as well as greater retention period on the otherwise fast flowing stream
- Installation of coir log bundles [using 75 logs dispersed and anchored at 20 locations] – coconut coir logs are biodegradable logs specially redesigned with coco-peat inside the core – serves as a medium for bacteria to reside, grow and treat the pollutants, serves as a filtering medium to certain extent, serves to reduce the velocity of water flow by obstructing the flow
- Installation of submerged Bio-Media – Two types of Bio-Media adopted – 1) Submerged Bio Media which serves as medium for anaerobic bacteria to reside, grow and treat the pollutants and – 2) Moving Bed Bio Media which serves as a medium for the facultative bacteria
- Manual removal of floating waste – this had to be done to provide an aesthetic appearance as well as retain operational efficiency and also avoid residents’ objections. However, this is strictly a municipal function which needs to be performed by Municipality regularly and effectively to prevent any solid waste reaching the Assi Nadi.
8.0 Why Bioremediation :
- Correctly speaking all sewage must be captured and taken to STPs [centralized or decentralized] for treatment and not allowed to flow through storm water channels. The exercise entails individual household connections, sewerage system, pumping stations, STP – a matter of few years [and being implemented for last 3 decades]
- Till such time pollution abatement essential and bioremediation as proposed provides effective solution
- Proposed solution can be implemented in a matter of 2 months and very economically
- Significant pollution reduction to the extent of 70% – rest can be taken care of by river’s own natural resilience and self cleansing capacity
9.0 Operations : The work of installing the interventions commenced in the last week of December, 2016 and was completed by 23 January, 2017. On 24th January, 2017 the bacteria concentrate dozing was commenced.
10. Even as early as 28th Jauary, 2017 residents along the Nadi reported substantial reduction in foul odour [interview with basti pradhan recorded] and their relief from the same and their positive impression of water quality improvement. Regular bathers at Assi Ghat also vouched for a palpable improvement in water quality.
11. Water Testing : Testing was carried out in December, 2017 before start of work and the results are as follows :
Water Quality Pre-Treatment
|Oil & Grease||mg/l||04|
Water Quality Intermediate Stage [6Feb/2017]
|Oil & Grease||mg/l||Nil|
Water Quality Final Stage [26 Feb/2017]
|Oil & Grease||mg/l||Nil|
|PARAMETER||Pre Treatment||Intermediate Stage [14 Days]||AFTER 30 Days Of Treatment||% REDUCTION ACHIEVED|
|Oil & Grease||04||Nil||Nil|
12. UK Choudhary, Environmental Expert with the Divl. Commissioner’s Committee surveyed the entire works on 21st February, 2017, took note of the responses of the residents and expressed his satisfaction with the work
13. On 5th April, 2017 the report was presented to Member Secretary, CPCB who expressed his approval of the same.
14. The cost of bioremediation treatment would be Rs. 4.24 Cr annually in the first year with cost reducing to Rs. 3.75 crores in subsequent years at constant price. This includes the cost of :
- garbage removal from the banks and from the stream
- deployment of sludge pumps to remove sludge settlement from behind the proposed weirs
- civil structures to capture untreated inflows in the last 300m stretch
- floating wetlands carrying cleaning plants
- planting of aesthetic riparian vegetation where possible
15. In contrast conventional treatment would require Rs. 75 cr. of capital equipment cost + plus land cost for 10 ha + annual O & M cost of Rs. 12 cr. + cost of trunk and branch sewers and individual household connections as well as sewage pumping stations – THIS IS A MATTER OF A FEW YEARS.
16. In the interim period the proposed treatment would provide relief to both the river and the citizens. If the proposed treatment is replicated on the several nalas and nadis outfalling in River Ganga the river would be significantly cleaner and resilient to handle the remaining pollutants
17. In the next stage it is proposed to provide floating plant wetlands as well in order to attain still better results. These would have to be in large numbers and require time for plants to mature.
Manu Bhatnagar, INTACH (email@example.com, Credit for all photos and maps to INTACH)